Reincarnation and stem cell research How do we apply reincarnation to phenomena such as reproduction by binary fission (amoeba) and creating animals like Dolly the sheep from a single cell? Also, why the population is rising in the animal kingdom including humans, surely, it cannot be other beings from different realms are coming to earth. I am so confused about this although I am a  practicing Buddhist.
How do we apply reincarnation to phenomena such as reproduction by binary fission (amoeba) and creating animals like Dolly the sheep from a single sell?Also, why the population is rising in the animal kingdom including humans, surely, it cannot be other beings from different realms are coming to earth.
I am so confused about this although I am a practising Buddhist.

If you want to become an even more confused Buddhist, then keep pondering this :)
If not, then stop pondering this and go practice.
You might also want to take a look at the Four Imponderables:

The four imponderables are identified in the Acintita Sutta, Anguttara Nikaya 4.77, as follows:
The Buddha-range of the Buddhas [i.e., the range of powers a Buddha develops as a result of becoming a Buddha];
The jhana-range of one absorbed in jhana [i.e., the range of powers that one may obtain while absorbed in jhana];
The [precise working out of the] results of kamma;
Speculation about [the origin, etc., of] the cosmos is an imponderable that is not to be speculated about.

These imponderables the Buddha advices not to contemplate, since they will only agitate and destabilize the mind, making it less suitable for practice.