[2] His grandfather Lee Seldin headed a motorcycle club, the Dragons, in Bedford Stuyvesant in Brooklyn, New York, during the 1950s.

[4][13][14] Seldin wears a Star of David on his trunks, as did former Jewish boxers Benny Leonard and Barney Ross.

[2] "Remember the Masada", a reference to the legendary mass suicide of Jewish rebels under siege by Romans in AD 74, is stitched on the back of his jacket.

[4] Seldin made his national television debut in July 2014 on ESPN against Bayan "the Mongolian Mongoose" Jargal (17–5–3, 11 knockouts) at the Paramount Theatre in Huntington, Long Island, New York.

[19] Seldin defeated him by a technical knockout in the ninth round, winning the World Boxing Council International Silver Light Welterweight (140 pounds (64 kg)) title.

[29] He is the reigning Super Lightweight Champion of the North American Boxing Association; in 2020 he broke his own record by winning 25 of 26 fights, with 21 knockouts, when he fought Luis Florez.

[30] On October 16, 2021, in the main event at TrillerVerz at Barclays Center in Brooklyn, NY, he knocked out Brazil's Willam Silva in the seventh round.