Lewis Hamilton says his Mercedes team-mate Nico Rosberg "complains a lot", following a tense season.
Relations between the two title rivals have cooled following a number of incidents in which Rosberg claimed Hamilton had driven too aggressively.
The world champion said: "You've seen he complains about a lot of things. But you kind of let it go over your head because that's just the way he is.
"It's kind of the different background we come from, I guess."
This is not the first time Hamilton has referred to the fact his parents split when he was young and he grew up on a council estate, while Rosberg spent his childhood in Monaco as the son of 1982 Formula 1 champion Keke Rosberg.
There have been a series of flashpoints between Hamilton and Rosberg this year, particularly at the Japanese and US Grands Prix, at both of which the German felt Hamilton had been too aggressive while passing him at the start of the race.
Hamilton, who was speaking in an interview for the BBC One F1 Review show to be broadcast on 12 December at 13:00 GMT, said: "On the racing side of things you have to be tough.
"You can't be nice out there, and go: 'Hey, here's some space.' I mean business.
"I'm not here to make friends, to finish the race and say: 'Hey, that was a lovely race, chap, you were so friendly with me, you let me win.'
"This is the one opportunity and you take it. That doesn't mean wiping someone out or cheating but you have to be fierce, strong and hard to as much of the limit as you can be.
"And you can ask every world champion, if you're on the outside, you have to back off."
The incidents at Suzuka and in Austin happened with Rosberg on the outside being forced off the track by Hamilton.
The Briton won the title in the US after Rosberg, having got back into the lead later in the race, made a mistake and ran wide, handing his team-mate victory.
In the pre-podium room afterwards, Hamilton tossed Rosberg the cap he had to wear on the podium, only for the German to throw it straight back at him.
Hamilton said he had had some second thoughts after forcing Rosberg wide at Turn One in America.
"I'm definitely a believer in karma, and while I didn't intentionally do anything, I felt afterwards: 'Ah, jeez.'
"The guys were on me, and then he got back in the lead and I thought: 'Well, that's karma, he's back in the lead so he should have nothing to complain about.'
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"And then eventually I got him back later on but still he had to find something to complain about."
Hamilton won 10 of the first 16 races of the season before Rosberg won the final three grands prix after the Briton had secured the title.
Mercedes F1 boss Toto Wolff has said this week he will consider replacing one of the drivers if their relationship starts to damage the team.
"We struggle sometimes in winning races on Sunday and having always one upset," Wolff told Motorsport.com.
"And this spills over into the team. It is something that needs to stop.
"We will consider if it is the best set-up for the team."
He also described the dynamic between the drivers as the team's "biggest weakness".
Rosberg's contract runs out at the end of next season, while Hamilton this year signed a new deal that lasts until the end of 2018.