The first birth in my Sims 4 game was the Goth family, and it was twin girls. Well, they're only toddlers now, so I'm not 100% they're identical, but so far they look identical. I still need to play them to childhood. I thought I had identical twins boys in The Sims 2 - at the toddler stage they looked identical, but their differences started to show as children. I may have some pictures somewhere of them, too (this was back in like 2007/2008... lol - interestingly enough, they are the brothers of my avatar!)