A son raised by two talented lesbians--Claire the photographer and Theo the gourmet chef and caterer--narrates this solid first novel. Much of the premise tends toward the unbelievable, particularly two women finding a way to practice artificial insemination in 1965 (the year Willy is born) and the narrator later running away from home and living with the homeless under the streets. Most often, however, the excellent writing carries off these implausible events. Then, too, since the adult Willy (now the father of twins) narrates the tale, it's possible that he may be relating a child's-eye view containing as much fantasy as fact. Either way, episodes like the story of Claire (his non-biological mother) using a bicycle to get a jar of donated sperm across town before it dies is a sufficiently captivating image. The same holds true for descriptions of the circle of eccentric, supportive friends surrounding Claire, Theo, and Willy. Rounding out this community are their two sets of parents: Theo's bizarre, free- spirited folks, who live in a trailer in Broken Arrow, Okla.; and Claire's uptight, Upper East Side mother and father. As for Willy, the most striking thing about him is his normality, since even in NYC his living arrangement was unusual--``In 1972 there were no picture books entitled Heather Has Two Mommies or Daddy's Roommate,'' he notes--and his elementary school days were less than peaceful, as he was taunted by classmates at the posh McCall School. Willy's candid voice is refreshing: While the details are occasionally precious, their narrator never is, and the story he tells moves steadily toward the inevitable family conflict that reflects the dissension growing between Theo and Claire as they discover that they have different ways of dealing with Willy's mistreatment at the hands of his peers. The fantasy and mythic weight of a fairy tale, undermined occasionally by cuteness.