OP here
Thanks for the reply.

First child in sibling/friend group gets it hard. One friend had her first child (3 years before any of us). We would talk about how bratty her kid could be. Jerky - we knew nothing about toddlers.

When children in sibling/friend group are same age, comparing or judging happens. My sister had her first child - six months later I had mine. My kid talked around the same times as hers. I commented on it because I was so excited - child is so verbal, child is so verbal.

Years later I saw how annoying and competitive that must have seemed.

Anyone else feel an increase in tension or competition with siblings after you both had children? I am experiencing this and do not know if it is a natural situation or related to a particular family dynamic..

My sister and I are from larger family - five children. Our parents made us feel pretty unique and loved and explicitly talked about not having favorites - each of us had space to shine and fail. Not that we did not compete, but on the whole were encouraged to try different and our own things. One had disabilities and learning issues, so maybe that created awareness of varied skills?

My sister's husband, my BIL, is from a family of two boys. BIL is clearly his mother's favorite. His family has a much more competitive vibe around who is "better." This is something my sister and I used to discuss as it seemed weird to both of us.

Fast forward- all my siblings and I have elementary aged children.

BIL really loves and is super involved with his kids, who are awesome. BIL seems to favor middle child (only boy who is also very competitive). BIL, after any event (family or friends) can be quite judgmental of other children, including his nephews nieces (both sides) and his children's friends (birthday parties etc). My sister does it now too. It is annoying. - again their kids are sweet and excel at many activities. - again their kids are sweet and excel at many activities.

I feel like this is introducing competition into my relationship with sister and her children... which makes me back off from talking to her and to BIL and therefore cousins have less time together.

This dynamic is not present with my other siblings and the other 6 cousins - I feel like each kid is kinda able to be his or her own self. Shares of successes and challenges, but not competition (I would say the older ones are entering a i wanna prove myself stage - but that is between cousins and seems appropriate.)

I mostly try to ignore it, but after the weekend it is bugging me. and I am missing my comfortable relationship with my sister where we can talk and make observations and talk about our kids .

Anyone else find an increase in competition between the adult siblings once new in-laws and children are involved?