Clearly you don't know what means the Word "Talent".
A person like Kenenisa not overweigth, at the age of 25 years, working as farmer (therefore, a manual job, where he needs to use energy), can easy run UNDER 15' in his first attempt on the distance.
Forget the idea that, with his talent, he has to spend one year for running 15', and start to think that the natural aerobic ability of the best runner all-time can produce, with no training, a performance that, for example in Italy, put him about position one hundred in the seasonal lists.
Don't do the mistake to think athletes of that level can reach their results because hard training only. In percentage, I give 80% to the natural talent, and 20% to their training, if carried out under a proper coach and in the proper way.
Without speaking about top levels, several years ago I had some Italian athlete, not runner, who decided to start at 23 years of age, went to the Track of Sisport Fiat for being tested, and ran 3000m in 8'52". At 27 he ran 13'23" (5000) and 2:11:51 (Marathon), at 28 ran 28'01" (10000) and at 30, 61'07" (HM).
One person every billion people on Earth can have Kenenisa's talent, and every comparison with normal people is a useless and stupid attempt.