Hip dysplasia is a common genetic trait of many dog breeds, but most common in large and giant breeds. (www2.vet.cornell.edu)
Some intended parents want to ensure the embryo carries or does not carry certain genetic traits or they may want a multiple birth. (canadianlawyermag.com)
Personality has more to do with genetic traits related to mood and energy (which plenty of research indicates are strongly influenced by genetics). (scientificamerican.com)