Would you be weirded out if you found out your fiancè slept in his parents bed until he was SEVENTEEN YEARS OLD???

I've been with my fiance for four years and we have a child together. We celebrated his mum's birthday and his aunt mentioned something about them finally cutting the cord. And how my fiancè slept in the bed with his mum AND DAD until hr was seventeen years old. That's like too old right? He told me that he started after they got reunified from the foster system. His parents were neglectful because of drug use. They got reunified after a couple years and they were sober. He and his siblings were taken and separated when my fiancè was ten and reunified when he was thirteen. I know foster care can be traumatizing my seventeen is way too old. I've been married before to a man who was a huge momma's boy and that is what broke out marriage. He refused to set boundaries with his mom. I like my in-laws but if they can't set boundaries at seventeen it makes me worry about the boundaries they will try to cross once we are married.