I was one of three (middle, large age-gaps) but honestly feel that the decision to have a larger family was a mistake on the part of my parents
They didn’t have the income, time or energy to properly pay attention to all three of us, even with a SAHM. I also noticed that ‘parenting fatigue’ set in when I was about fourteen and they were 50ish - but they still had nearly a decade to go at that point to raise my younger sibling!
We were good, hardworking, studious DC who did well at school but there were still periods when each of us was (relatively) neglected due to our parents not having the capacity to notice or take action, because they were so tied up with another child. Or the general assumption that we must be ‘alright’ and getting on well at school, because, why wouldn’t we be? Depression, bullying, sexual harassment, untreated infections, medical problems that they were too slow to take to the GP…One of my siblings has lifelong MH problems that started in their teenage years. Plus they completely failed to plan for university costs for all three of us, despite my father being over the threshold for us receiving any kind of funding…
Read one of the Higher Education threads about sending DC to university if you’re thinking of having three close together! There was a recent thread about two DC going to Bristol which was very eye-opening. Be warned, the student finance system takes no account of the costs of multiple children going through university at the same time!
Also, life happens - one of my parents had a cancer diagnosis when we were 17, 10 and 6, which probably contributed to some of the above, but I suspect it still would have been easier for them with two rather than three children.
I look now at the level of support, attention and focus that I have been able to give my own DC (whose own path has not been straightforward) and wish that I had received a bit more of the same.