Various Wiccan traditions hold a wide range of differing beliefs about sexual orientation. Gerald Gardnerthe founder with Doreen Valiente of Gardnerian Wiccaparticularly stressed heterosexual approaches to Wicca,  whereas Alex Sandersthe founder of the Gardnerian offshoot, Alexandrian Wiccacame out as bisexual later in life and created new rituals in which sexual orientation was irrelevant.
Gardnerian Wicca and other more traditional groups form their covens from male-female pairs. The witches tell me 'The law always has been that power must be passed from man to woman or from woman to man, the only exception being when a mother initiates her daughter or a father his son, because they are part of themselves' the reason is that great love is apt to occur between people who go through the rites together. They go on to say: However, the above quote is in the context of a section in Gardner's book examining why the Templars were executed by Gardner himself, so it is entirely possible that the reference is to Gardner's own opinion of homosexuality.