Power boats and hit singles aside, life hasn't all been smooth sailing for Jacks. His marriage to Pesklevits dissolved in 1973. A second marriage produced a daughter, Holly, and later charges of spousal abuse. According to Canada's CNEWS, when officers in Sechelt, British Columbia, arrived at Jacks' home in 2001, they leveled a charge of improperly storing a firearm against him in addition to the abuse charge, although the rifle was not related to the alleged assault.

As a youth, Jacks resisted family pressures to turn him into an architect. Favoring music instead, he joined the Vancouver-based Chessmen, playing guitar and providing vocals on a pair of singles released by London Records and on two more released by Mercury Records during the mid-'60s. Jacks met his first wife through the Chessmen's appearance on Music Hop, a Canadian television program. Eventually the pair formed the Poppy Family after recruiting guitarist Craig McCaw and Satwant Singh, who played the tabla.

Before "Which Way You Goin' Billy" landed the group in the spotlight, Jacks and the Poppy Family released two singles that didn't go anywhere, "What Can the Matter Be" and "Beyond the Clouds." Later they scored two lesser hits, "Where Evil Grows" and "That's Where I Went Wrong." But Jacks did not take well to performing live. That aversion, coupled with the pressures of stardom, led to his decision to break up the band. In 1973, he produced his wife's eponymous debut album and wrote one of the songs, "I Thought of You Again," which garnered a Juno Award nomination. Despite their working relationship, or perhaps because of it, Jacks and his wife split that year.

A major concern for the musician is environmental pollution, and he has transformed himself into something of a major obstacle for large-scale pulp and logging companies that are suspected of noncompliance with Canadian pollution laws. To that end, he established an organization called Environmental Watch.