Gay actor Stanley Bennett Clay, who was friends with both men, revealed in a 2007 interview that Raymond and Sterling were in a romantic relationship. Raymond's claims about Sterling being his adopted son or nephew were just to protect the relationship from scrutiny. Both men died of AIDS related complications.
From wikipedia: "St. Jacques was a lifelong bachelor. By the early 1970s, St. Jacques claimed to have two older sons, Raymond, Jr and Sterling. In a 1973 interview, St. Jacques claimed that Raymond, Jr. was living in Boston. In May 1972, Sterling, then reported to be 22 years old, made news after four men attempted to rob St. Jacques' Bel Air home. Sterling was the only person home at the time (St. Jacques was in Dallas at the time) and fled after calling police. The four men were apprehended after their getaway car stalled in St. Jacques' driveway. Sterling went on to appear in St. Jacques' 1973 film Book of Numbers. In the mid to late 1970s, Sterling became known as a high fashion model (he was briefly engaged to fellow model Pat Cleveland), dancer and a frequent New York City nightclub and society fixture. In her 2016 memoir Walking with Muses, Sterling’s ex-fiancée Pat Cleveland stated that their engagement came to an end because Sterling was gay. Sometime in the early 1980s, he moved to Europe where he found moderate success as an Italo disco singer. Sterling St Jacques reportedly died of complications of AIDS in 1990 (his death has never been officially confirmed and his true fate remains unknown). However, in a 1988 interview with the Chicago Tribune, St. Jacques still claimed to have two sons and said Sterling was appearing on a television show in Düsseldorf. The adoption of Raymond, Jr. and Sterling was apparently never official. In his will, St. Jacques claimed that he had no children and named only Sterling, whom he identified as his nephew, in his will. St. Jacques bequeathed Sterling $1 from his $750,000 estate. One of the pall bearers at the funeral was Stanley Bennett Clay, who later revealed that St. Jacques had not been Sterling's adoptive father but his sugar daddy, but that they later had a falling-out."