Comparing Your Child to Their Sibling
Medically reviewed by Dr. Emily Torres, PhD, CCC-SLP · Pediatric Speech-Language Pathologist
Content reviewed against published AAP, CDC, NIH guidelines
Last reviewed:
Behavioral development varies greatly from child to child. If you have noticed comparing your child to their sibling, here is what you need to know.
The short answer
Comparing your children to each other is one of the most natural things a parent can do, but it is also one of the most misleading. Every child follows their own developmental timeline, and siblings can differ dramatically in when they walk, talk, or reach other milestones, even when raised in the same household. These differences reflect normal biological variation, not a problem that needs fixing.
Key takeaways
- Comparing your children to each other is one of the most natural things a parent can do, but it is also one of the most misleading. Every child follows their own developmental timeline, and siblings can differ dramatically in when they walk, talk, or reach other milestones, even when raised in the same household. These differences reflect normal biological variation, not a problem that needs fixing.
- Usually normal when: Your children reached the same milestones at different ages but both within the accepted normal range
- Call your doctor if: Your child has lost previously acquired skills such as words, social engagement, or motor abilities
- Varies by age — see the age-by-age breakdown below
This is one of the most common questions parents ask. Searching for answers means you care.
What Parents Should Know
According to AAP, CDC, NIH guidelines, comparing your children to each other is one of the most natural things a parent can do, but it is also one of the most misleading. Every child follows their own developmental timeline, and siblings can differ dramatically in when they walk, talk, or reach other milestones, even when raised in the same household. These differences reflect normal biological variation, not a problem that needs fixing. At 0-3 months, in the earliest months, parents often compare how their newborn feeds, sleeps, and fusses compared to an older sibling at the same age. It is important to remember that your memory of your first child's infancy is likely imprecise and filtered through the fog of sleep deprivation. Each baby has a unique temperament from birth, and differences in alertness, fussiness, or feeding patterns are expected. It is generally considered normal when your children reached the same milestones at different ages but both within the accepted normal range. However, you should contact your pediatrician promptly if your child has lost previously acquired skills such as words, social engagement, or motor abilities.
Normal vs. Concerning
By Age
What to expect by age
0-3 months
In the earliest months, parents often compare how their newborn feeds, sleeps, and fusses compared to an older sibling at the same age. It is important to remember that your memory of your first child's infancy is likely imprecise and filtered through the fog of sleep deprivation. Each baby has a unique temperament from birth, and differences in alertness, fussiness, or feeding patterns are expected.
6-12 months
This is when motor milestone comparisons tend to peak. If your first child sat at five months and your second has not at seven, it is easy to worry. Normal sitting ranges from four to nine months, and normal crawling has an even wider window. Birth order, temperament, body type, and opportunities for practice all influence when milestones appear. Focus on whether your child is progressing, not on the exact timeline.
12-24 months
Language and social comparisons often dominate at this age. Second-born children sometimes talk later because older siblings anticipate their needs, or they may talk earlier because they have a constant language model. Walking timelines can vary by months between siblings. What matters is whether your child is within the broad range of normal, not whether they match their brother or sister.
24-36 months
By toddlerhood, personality and interest differences become more apparent. One sibling might be a voracious eater while the other is picky. One might be physically adventurous while the other prefers books. These are expressions of individuality, not developmental red flags. If you have specific concerns about delays, discuss them with your pediatrician based on standardized developmental benchmarks rather than sibling comparison.
What to Tell Your Pediatrician
- Describe when you first noticed comparing your child to their sibling and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if your child is significantly outside the expected developmental range for their age, regardless of sibling comparison.
- Mention if your anxiety about the comparison is affecting your ability to enjoy your child or parent confidently.
- Bring a list of any questions or observations you want to discuss at the appointment.
What Should You Do?
When to take action
- Your children reached the same milestones at different ages but both within the accepted normal range
- Your second child has a different temperament or personality than your first
- One sibling excels in physical milestones while the other is stronger in language, or vice versa
- You occasionally feel worried but can remind yourself that variation between siblings is expected
- Your child is significantly outside the expected developmental range for their age, regardless of sibling comparison
- Your anxiety about the comparison is affecting your ability to enjoy your child or parent confidently
- You notice your child is losing skills they previously had, which is different from being slower than a sibling
- Family members are frequently making comparisons that are causing you stress or concern
- Your child has lost previously acquired skills such as words, social engagement, or motor abilities
- You notice developmental warning signs that are concerning independent of any sibling comparison, such as no babbling by 12 months or no words by 16 months
What You Can Do at Home
- Keep track of when you notice comparing your child to their sibling — noting the time of day, duration, and any triggers can help your pediatrician.
- Remember that your children reached the same milestones at different ages but both within the accepted normal range — this is generally within the range of normal.
- At 0-3 months, focus on observation rather than intervention unless your pediatrician advises otherwise.
- Respond consistently and calmly to your baby's behavior. Maintain predictable daily routines.
- While monitoring at home, seek immediate care if your child has lost previously acquired skills such as words, social engagement, or motor abilities.
Related Resources
Frequently asked questions
Is comparing your child to their sibling normal?
When should I call the doctor about comparing your child to their sibling?
When is comparing your child to their sibling normal?
What causes comparing your child to their sibling?
What should I mention to my pediatrician about comparing your child to their sibling?
Is comparing your child to their sibling normal at 0-3 months?
Is comparing your child to their sibling normal at 6-12 months?
Should I go to the ER for comparing your child to their sibling?
Does comparing your child to their sibling go away on its own?
References
Doctor Visit Checklist
Bring this checklist to your next pediatrician visit to discuss Comparing Your Child to Their Sibling.
Things to mention
- Describe when you first noticed comparing your child to their sibling and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if your child is significantly outside the expected developmental range for their age, regardless of sibling comparison.
- Mention if your anxiety about the comparison is affecting your ability to enjoy your child or parent confidently.
- Bring a list of any questions or observations you want to discuss at the appointment.
Observations to share
- Your child is significantly outside the expected developmental range for their age, regardless of sibling comparison
- Your anxiety about the comparison is affecting your ability to enjoy your child or parent confidently
- You notice your child is losing skills they previously had, which is different from being slower than a sibling
Urgent signs to report immediately
- Your child has lost previously acquired skills such as words, social engagement, or motor abilities
- You notice developmental warning signs that are concerning independent of any sibling comparison, such as no babbling by 12 months or no words by 16 months
My notes
From ismybabyalright.com — free, evidence-based baby health guides
All content follows our editorial policy and is reviewed against published clinical guidelines.
2,705 evidence-based guides6 authoritative medical sources5 medical advisory board members
Related Resources
Bottom line
Most cases of comparing your child to their sibling are normal. Talk to your pediatrician if your child has lost previously acquired skills such as words, social engagement, or motor abilities.
Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.
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