The most difficult for any MBBS student is understanding the complexity of genetic disorders, neoplasm and the diagnosis of them. But I would rather say genetics and genomics is simple mathematics, they are like:
2+2 = ?
So simple. The only few basic you got to know from them is What is 2? in genetics. If you know them then you master them.
Check the most basic video on MEIOSIS below. Go through it first, it may sound unimportant but they are definitely needed to understand genetics.