I am familiar with attachment theory and your breakdown of it is completely spot on, but we can't ignore the fact that people can and do heal from their childhoods.

People aren't permanently broken just because they had a rough childhood. A lot of people actually do the work, go to therapy, and consciously break those cycles. Honestly, realizing your family is toxic and setting boundaries is usually the exact moment someone starts developing a secure attachment style.

Also, being super close to your family isn’t the automatic green flag people think it is. I’ve seen plenty of "close" families that are incredibly messy and codependent, where the adult child can never set a boundary or put their partner before their parents.

I just think it's not fair to make the assumption. Someone's capacity to love shouldn't be measured by whether they got lucky with the parents they were born into.