In almost all organisms, every cell contains identical genes — it is a difference in gene activation that distinguishes a blood cell from a nerve cell. (sciencedaily.com)
Even when fathers and mothers contribute identical genes to their offspring, the genes may have different effects. (scientificamerican.com)
In the not too distant future people with 25 % or more identical genes are not allowed to have children together. (rottentomatoes.com)