cap said:

Force sensitivity is an inherited trait.

So of the people with the greatest potential to become Jedi, most would be the offspring of Jedi... except that Jedi are forbidden to marry, and presumably to reproduce.

Do the Jedi want to limit the power of future generations of the Jedi order? Why do they limit their own growth this way?

Perhaps yes, the Jedi might want to limit the power of future generations of Jedi. Perhaps their prohibition on marriage is only partly out of a desire to avoid attachment. Perhaps it's also a willful limit on the birth of a caste of superpowered demigods, when the Order's desire is to preserve the peace and serve the Republic.