"Yeah that'll do it. Humanity interfering does that at home too, even before we did science we made dogs outta wolves. And nowadays most things have been genetically engineered. So, the way we discovered all this is long-winded, but bodies are made up of cells, small enclosed life forms that cooperate to make one big being. There's a structure called deoxyribonucleic acid, DNA, inside the cells, and that DNA describes instructions for how the cell should assemble proteins. Proteins do all the heavy lifting of cells being alive. Change the DNA, change the being carrying it. DNA is ultimately just an absurdly long string of pieces stuck together that can have one of four values on each piece - libraries and libraries full for even the smallest creatures. The cells in the main body have full copies. Reproductive cells have half copies, assembled semi-randomly, it's complicated. And when the gametes combine they assemble into one full copy that has pieces from both the father and mother. Some traits involve just one tiny piece of DNA and will show up in kids by a pattern called a Punnet square, after the guy who figured it out I think, but some are influenced slightly by lots and lots of pieces spread all throughout, or by how well a kid eats growing up or whatever, and vary a lot. Like height. There's lots of complications but that's the basic idea."