“American Beauty” screenwriter and “Six Feet Under” creator Alan Ball adapts and directs Alicia Erian’s novel “Towelhead” for a coming-of-age story. Set in a Texas suburb during the first Gulf War, this black-ish comedy of sexual manners stars Summer Bishil as 13-year-old Jasira. Her first period, first orgasm and first age-inappropriate partner in intercourse arrive in rather short order. The plot empowers Jasira with uncommon control of her sexuality. Her mom’s boyfriend agreed to shave her thighs one day, which spelled exile from Syracuse to her dad’s strict, if double-standard, household in Houston. Dad (Peter Macdissi) is a testy Christian from Lebanon who works for NASA as an engineer. Monitoring the trajectory of his estranged daughter’s emerging maturity—what are you doing with Playboy magazines?—throws him in a state of patriarchal panic. Jasira draws the attentions of her new neighbor, an Army reservist (Aaron Eckhart), and an African-American classmate (Eugene Jones). What is intriguing about Jasira’s character is how purposively she seeks or dodges their sexual interest. She almost knows what she’s doing. An occasional outburst of silly girlish thrill on her face belies her womanhood. On her own she acquires a knack for masturbating by deftly grinding her thighs under the lunch table at school. A vigilant and pregnant neighbor (Toni Collette) steps in for some timely feminine mentoring, not to mention legal counsel on statutory rape. Ball and Erian create nicely intricate characters for an ensemble exercise in multicultural trespass. With Maria Bello, Gemmenne de la Peña, Carrie Preston and Lynn Collins. 116m. (Bill Stamets)