My neurotypical brother came along just shy of 4 years after AuDHD me :)

My answer is very similar. My older son has ADD. My youngest has autism and intellectual disability. Probably there are a lot of factors but I also wonder if my age and my husband's age play a factor. I have been told by medical professionals that female children are statistically less likely to have autism....

My oldest son is autistic, oldest daughter neurotypical, youngest son is autistic, and youngest daughter neurotypical.

I had Liam when I was 36 and my husband was 48.

My first child has ADHD, but my 2nd child was born Autistic. It likely was partially due to my age being 41 when I had my 2nd.