A woman has called out Southwest Airlines for a "demeaning" experience she had with her son.
California woman Lindsay Gottlieb was set to travel with her husband Patrick Martin and son Jordan Peter Martin, 1, from Denver International Airport on a Southwest Airlines flight.
But the family was stopped by an airline official, who asked Ms Gottlieb to "prove" she was the mother of her biracial son.
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Ms Gottlieb, who coaches the women's basketball team at the University of California, claims the airline official requested to see her son's birth certificate and asked if she could prove their relationship with a social media post.
According to a tweet Ms Gottlieb posted on Monday, the employee justified their actions by citing "federal law".
Although providing a passport that verified her son's age and identity, Ms Gottlieb told The Washington Post she was "still pushed further" to prove that she was the mother of her child.
She said it felt "disrespectful and motivated by more than just concern for his well-being."
"My guess is because he has a different skin color," Ms Gottlieb speculated on Twitter, despite the airline official telling the woman the extra documentation was requested because the mother had a different surname to her child.
However, Ms Gottlieb says another woman traveling with her child wasn't asked to provide further evidence of their relationship despite having different surnames.
The airline has apologised for making the "family uncomfortable".
"That is never our intention," officials said, adding that the incident will be treated as a learning curve for their employees.
"I hope the coverage this has received can serve as a learning opportunity and that all families - regardless of how 'traditional' they may or may not look - are treated with dignity and respect," said Ms Gottlieb.