I wanted to make a couple from the rainbow slider who would have differently coloured babies. They are made from the opposite ends of the rainbow slider in CAS, he's red and she's more pink.
You need World Adventures, Ambitions, Late Night, Generations, Pets, Showtime, Superatural EPs and Master Suite SP.
In this picture they've just made their rainboo, lol.

Redd Mann
athletic, brave, charismatic, easily impressed, family-oriented. His LTW is 'surrounded by family'. His favourites are: ratatouille, indie and hot pink. He is a leo.
Magenta Mann
ambitious, athletic, charismatic, eco-friendly, family-oriented. Her LTW is also 'surrounded by family. Her favourites are hamburger, indie, aqua and she is an aries.
This is their baby Friday (awwww), born in game, just to prove that they do have different colour babies (I wasn't sure). Friday doesn't come with the couple, I thought people would want the couple to have rainboos when they were ready. It's tough to have nooboos straight away.

Friday as a toddler - Mum's eye colour, Dad's hair

Hope I've done this right. I've also uploaded them to the official exchange.
http://www.thesims3.com/assetDetail.html?assetId=6600041