The father of world 100m champion Justin Gatlin says the booing of his son is “disrespectful to the sport”.
“He served his ban and he worked his heart out doing what he could,” said Willie Gatlin.
“He worked to come back, and he worked his way back to championship form.”
Gatlin, 35, clocked 9.92 seconds as he beat second-placed compatriot Christian Coleman and legendary Jamaican Usain Bolt, who was third.
Bolt, 30, was unable to secure a 20th global gold in his final individual 100m race before retiring.
Lord Coe, president of the International Association of Athletics Federation, told BBC Radio 5 live’s Sportsweek Gatlin’s victory was “not the perfect script”.
He added: “I’m not eulogistic that someone who has served two bans has walked off with one of our glittering prizes.”
Willie Gatlin said he was not “upset” by his son being booed because “I know what kind of son I raised, what kind of character he has”.
He added: “The fans booing is disrespectful to the sport. The sport has always been here and is going to be here after he leaves.
“He created a memory that is going to be in people’s minds a long time.”
Why was Gatlin banned?
In 2001, when he was still at college, Gatlin was given a two-year suspension for taking a banned amphetamine.
He successfully argued this was due to medication he took for attention deficit disorder and was allowed to return to competition after a year.
Then, in 2006 – having won the 100m and 200m double at the 2005 World Championships in Helsinki – he tested positive again, this time for testosterone.
Gatlin was banned for eight years, avoiding a lifetime ban in exchange for his co-operation with doping authorities. This suspension was halved to four years on appeal.
“For the youngsters coming up, he is trying to help to tutor and help to be good, clean athletes,” added his father.
“He is trying to teach good character and good sportsmanship about themselves.
“I don’t think he has regrets, it is a lesson learned. Everything happens for a reason and it gives you teaching moments. We have been through it all and we bear it all.”
‘Boo the federations’
Toni Minichello, who coached Britain’s former Olympic heptathlon champion Jessica Ennis-Hill, says fans are entitled to express their opinions – but adds the authorities also need to be held to account.
“It’s not his [Gatlin’s] fault in any way shape or form,” he said. “It’s the fault of the federations and Wada [the World Anti-Doping Agency] for putting the rules down in such a way that allows him to return.
“Really, if you want to boo somebody, boo Wada, boo the federations.”