I made a female sim, moved her into Twinville, and got her married a week or two later Goodwin (he had a child son with his girlfriend). My sim had already maxed inventing, so they tried for baby in the past. 12 hours later, Star, a young adult, came out of the time machine saying "Mom, dad, this is much better than the cave you left me in!". I couldn't pick her traits and lifetime wish, buy she did come with some cool clothes from the past. In the family tree, Star was listed correctly. Then the mom and dad had a baby in the present ( something cool- the mom went travelling to the future, and now has future clothing) and then the parents tried for baby in the past again and got a teen boy named Monty (in past clothing). Monty was listed as being younger than the baby in the family tree. Then, they tried for baby in the future and had twin elder girls in future clothing (they came out of the time machine one right after another.) I kicked the past an future people out (one got a job as a fireman and two got boyfriends) and had more children. In the end, I had three future sims (all elders, 2 female, 1 male), 3 past sims (2 YA, 1 teen, 2 female, 1 male) and 4 regular kids.
As for genetics, all the kids got hair and/or eyes from their parents and the skin blending is working much better.