1,925. Men Who Can Only Perform Yibum (But Not Chalitzah)

Yibum v’Chalitzah 6:2

A man who is congenitally impotent and a hermaphrodite have no obligation in yibum because at no point were they able to father children.

Yibum v’Chalitzah 6:3

The following brothers are able to perform yibum but not chalitzah: a man with congenital deafness, a man lacking mental competence and a minor*. This is because they are presumed not to have the understanding necessary to perform chalitzah. If a man with congenital deafness performs yibum, he can never divorce the yevama; his intimacy with her effects a complete marriage bond and he is halachically incapable of effecting divorce. If a minor of nine years and a day performs yibum*, he cannot divorce her until he reaches the age of majority, as has already been discussed.

*The intention of the halacha is not to recommend such a thing, merely to address the halachic impact should it occur.