Here's a wonderfully well written analysis on all six Star Wars movies. It takes a look at the impact of Episodes I-III on the previously released Episode IV. Great stuff indeed.
" Obi-Wan has spent the last 20 years in the Tattoine desert, keeping watch over Luke Skywalker and trying to decide on one of the three available options:
A) If Luke shows no significant access to the Force, then leave him alone in obscurity
B) If Luke shows real Force ability, then consider recruiting him as a Jedi. The rebellion needs Jedi. Now.
But, if Luke shows any signs of turning out like his father, then C) sneak into his house one fine night and chop his head off. With great regret but it'll save a lot of trouble later on.
Knowing this to be the case, Bail Organa (perhaps at the insistence of his wife) has found excuses not to send Leia to Ben for assessment of Jedi potential, largely for fear of option C."