Nobody imposes on the soul. The soul itself makes the choice, but it has to be approved by the Supreme. The soul, while sitting at the top of the tree, feels that if it comes down to earth, it will be able to fulfil itself. But, as you know, the world is full of imperfections and limitations. And when the soul touches the foot of the tree, it feels that there are all unlit forces, evil forces, trying to capture and devour it. So after making the choice, sometimes the soul feels that the environment it has chosen is unhealthy, and it may leave the body.
?Sri Chinmoy, Death and Reincarnation
Usually, a soul follows continuously the same line of sex. If there are shiftings of sex, it is, as a rule, a matter of parts of the personality which are not central.
?Sri Aurobindo, ?A Practical Guide to Integral Yoga?.