No, one study doesn’t upend the last few decades of understanding of emotional attachment.

The study simply says that ability to connect w friends is more predictive than observations they made of apparent attachment of parents.

This happens much later so of course it’s more predictive of the actual end effects - that’s when attachment styles actually show up for the first time. Kids grow up to be very adaptive toward their parents but when they get to the rest of society that’s when the failures of connection and the failed bids for attention show up.

A very resilient kid will do fine with friends even with a very bad attachment environment. A very sensitive kid or one with developmental problems will struggle in social environments.

I'm not a psychologist or psychiatrist. My observation is the more difficult cases of attachment in important adult relationships esp. partner/spouse is far more impacted by parents and their relationship than friends.

This doesn't gain say that in the ages of 15 to say 35 peer interactions are not there or impactful to the worse or better but extremes in the nuclear family are not to be underestimated.

Also, even the proposed effect is modest:

> But early friendship bonds played an even bigger part than maternal relationships in the ways people navigated adult friendships and romantic partnerships, accounting for 4 percent of the variance in adults’ romantic partner- and best friend-specific attachment anxiety, and 10 to 11 percent in their partner- and best friend-specific avoidance.

Just slightly less modest that analogous parental predictors, according to their claims.

One study doesn’t definitively prove anything, but this is a 30 year longitudinal analysis with 700 participants. It’s way bigger than a typical study

also given the psychology field research replication crisis, I would wait to see if this research can be replicated down the road.