[AntiGuv]

There is only one problem with these donkeys theory. White skin genes aren't dominant.

Well, one problem with your problem is that recessive genes don't vanish, and in some cases no doubt thrive.

Assuming that a recessive gene appeared in one person, then the offspring of that person would have the recessive gene even if they did not express it. Some number of their offspring would also have the recessive gene, and sooner or later you will get individuals that express the recessive trait. If natural selection (including sexual selection) then favors those individuals then the gene will eventually predominate in the population.

[Seven Minute Maniac]

Having 5 fingers is a recessive gene, the dominant is a smaller sixth between the ring and pinky fingers.

[A6M3]

They don't vanish, but they may not appear again in a thousand years, or ten thousand years, if ever.

[Eclectica]

Assuming that a recessive gene appeared in one person, then the offspring of that person would have the recessive gene even if they did not express it. Some number of their offspring would also have the recessive gene, and sooner or later you will get individuals that express the recessive trait. If natural selection (including sexual selection) then favors those individuals then the gene will eventually predominate in the population.

Never mind all this.

Can adult stem-cell insertions save me all that time I spend trying for a perfect tan?

I need more time to get ahead of the Jones'!