Complex sentence: Acceptance of God's will is seen as central in Sikhism, thus even if a Sikh is attracted exclusively to members of their own sex they are expected to accept God's will, which in the teaching of the Granth is for them to procreate.
Split into simpler sentences: Acceptance of God's will is seen as central in Sikhism. Thus, even if Sikhs are attracted exclusively to members of their own sex, they are expected to accept God's will-which, according to the teaching of the Granth, is for them to procreate.