Ooh, very tough question. Honestly, this might not seem that interesting on the surface, but evolution itself is so fucking amazing. Just the sheer amount of time it took boggles the mind. Here, I'll share one of my favorite quotes from Bill Bryson to demonstrate the point:

Welcome. And congratulations. I am delighted that you could make it. Getting here wasn’t easy, I know. In fact I suspect it was a little tougher than you realize. To begin with, for you to be here now trillions of drifting atoms had somehow to assemble in an intricate and intriguingly obliging manner to create you. It’s an arrangement so specialized and particular that it has never been tried before and will only exist this once. For the next many years (we hope) these tiny particles will uncomplainingly engage in all the billions of deft, cooperative efforts necessary to keep you intact and let you experience the supremely agreeable but generally underappreciated state known as existence. Not only have you been lucky enough to be attached since time immemorial to a favoured evolutionary line, but you have also been extremely-make that miraculously-fortunate in your personal ancestry. Consider the fact that for 3.8 billion years, a period of time older than the earth’s mountains and rivers and oceans, every one of your forebears on both sides has been attractive enough to find a mate, healthy enough to reproduce, and sufficiently blessed by fate and circumstances to live long enough to do so. Not one of your pertinent ancestors was squashed, devoured, drowned, starved, stranded, stuck fast, untimely wounded, or otherwise deflected from its life’s quest of delivering a tiny change of genetic material to the right partner at the right moment in order to perpetuate the only possible sequence of hereditary combinations that could result-eventually, astoundingly, and all too briefly - in YOU.

In terms of understanding concepts -- Genomic imprinting took a while. The main idea is that the alleles you inherit from your parents weirdly "know" which parent they came from, and sometimes alter the development of the fetus/child based on that parent's evolutionary desires. It's super weird. For example, there are two diseases called Angelman Syndrome & Prader-Willi syndrome. These are both associated with the same chromosomal region. If you inherit a deletion in this area from your father, you have an insatiable appetite and are generally a difficult baby (demand a lot of resources from the mother). If you get it from your mother, you have a "perpetually smiling facial expression" and generally demand less (along with other stuff). Crazy shit!