Steve Trevor has an older brother who in 1943 had white hair. [“The Talking Lion,” Sensation Comics #17 (May, 1943)]
He has a niece named Ginger Trevor who in 1943 was a little blonde girl. [“The Talking Lion,” Sensation Comics #17 (May, 1943)]
He has another niece named Dotsie who in 1944 was a little redheaded girl. [“Evolution Goes Haywire,” Wonder Woman #9 (Summer, 1944)]