An apposite one - If I knew the answer, I'd be a millionaire. Control it, I could hire Bill Gates as my pool boy.
There are three factors that influence who you fall in love with. Chemical, psychological and, for want of a better word, spiritual.
Chemical is definitely a huge part of falling in love. Not just pheromones to attract you, but the various sex hormone levels and the unholy trinity of oxytocin, seratonin and dopamine levels play a huge part in falling in love.
Then there is your psyche. Expectations, hang-ups, quirks and sub-concious thoughts from your past, way back into earliest childhood from every person you have ever dealt with in any way. That has a strong influence on who you are initially attracted to.
But we are not just machines, hence the third aspect - the spiritual. The thing that is inexplicable yet makes us more than the sum total of our chemistry and experience, alloing us to go against chemistry and our psyche as we wish.
Most people in your situation blame chemistry. It is the easiest thing to blame.