What's this identical twin thing about?

I don't know if you've seen the recent Horizon TV programme on the effects of Fat and Sugar in Western diets [Horizon Sugar v Fat - What's worse for us: sugar or fat?], it was broadcast this week on BBC 2 and what I would say is that it came to the conclusion that we should avoid too much processed food as well as 'Fad' diets.
Okay so good stuff but not too surprising (I think ) to most of us and particularly to those working in the relevant fields.

What it stimulated in me was questions about what we can learn from 'identical' twins, if there is or was a supreme creator(s) what are they giving us clues about with this phenomenon or statistical  occurrence?

The  fact that two 35 year old Identical twins were still looking remarkably similar after so long and both pursuing careers in medicine is I think so much more than coincidence - but how much are we what we inherit and how much does the environment and our socialising determine outcomes?

There are many studies of twins and identical twins and some interesting points arise:

There are two cases where both brothers of identical twins have been charged with rape (one case in France and the other in the UK) the DNA evidence strongly suggests that one of the brothers in both cases committed the rape but DNA in identical twins is the same -it seems advances in DNA analysis may ultimately help differentiate between the  twins in such cases.

These cases though themselves raise issues about why which of the guilty twins behaved as they did (as opposed to the non guilty one), how did their upbringing or circumstance cause or influence the behaviour?

It seems that for 'twins' growing up together there are often some difficult identity issues where they see that they have their individual identity submerged in being part of a single entity - some anecdotal evidence here.

Professor Kandel points out here that brains are different in Identical twins and here's an article about how divergence develops.