...a very good question. If your wife has showed you that your parents are your enemies (joke!) and you cant buy them even a kg of sugar, then he has all the reasons to sell you the land. But if you support him, then you need to take him to mathare for a head overhaul!!!

YES YOU CAN, controversial as it may. Whats wrong with that? Your dad wants out of an investment, maybe to invest elsewhere, u can buy it if u want. At times we think we own what our parents own, in which we are totally wrong. In fact, you are likely to fetch a good price! However, the whole family must be involved.....kama mandugu watakataa, dont touch. My thoughts.

buying land from your father is very normal.
Just to echo @Simonkabz sentiments,your father may be wanting cash to venture or inject to another business but the only option is to sell one (of maybe)many plots,land parcels he has,to me i do not think this is wrong.If you are son/daughter,you have the right to buy just like any other kenyan.

my father does it (i mean sale his properties to my bros and sis) and i dont see anything wrong with it.

Willin buyer, willing seller. Cool.