global warming, evolution (still), minding your own business…haha (i included the last one because i think it basically includes gay marriage, religion, abortion, etc)
Mainly issues in the field of bioethics imo – human genetic engineering, cloning, stem cell research, euthanasia and so on… any act that involves interfering with human life, especially the DNA imo.
Not so much one idea but those issues pose very polarizing questions to humanity because of the incredible benefits and dangers of this field.
The answers to those two questions seem to me to be the basis of many of the disagreements above, based on religion, church & state, gay marriage, stem cells, abortions, etc.