I can say this comment doesn't comport with my experience. The kids are alright.

One old practice that has helped a lot is pair programming. I employ strong-style pairing when I work with a new hire which helps them ramp up on our practices quickly IME.

A new practice which has helped immensely are in-person "burst weeks" every 3 months or so. It isn't the same as spontainiously grabbing drinks after work, but it definitely helps to build team camaraderie.