Alan Harper is a chiropractor in Malibu who, after being divorced by his Judith, now lives with his bachelor brother Charlie in his Malibu beach-house. Alan is a shy person, especially compared to his brother, and his little luck with the ladies.
His life is generally him being humiliated by his ex-wife Judith, his mother Evelyn, his brother Charlie, his brother's maid Berta and his son Jake.
Alan's sexuality has been debated many times, while he is certainly a confirmed-heterosexual he has himself considered that he might be gay and that might be the reason for his lack of success with women. In the end, he wasn't gay just bad with women.