User blog comment:Jack Pistol/Immortal Dovahkiin?/@comment-75.139.209.199-20121003180320/@comment-2.217.54.83-20121004204752

If the Dragonborns were sterile, then there wouldn't have been any Septim emperors, and yes, that includes Talos too...

Dragonborn is pretty much a genetic gift, may not fall to all children within a family, but still genetic, they did originate from Akatosh and St. Alessia "covenanting". So, it had to be passed on some other way.

Also, making players adopt children is just so they don't have to skip the game's time to 9 months later, or longer until it's a child model, and make other child versions of non-human children... as well as let same-sex couples have kids... mostly the game time & child model thing.