A California mother is reminding the world (and specifically, airline employees) that resemblance isn’t what makes a family.

Lindsay Gottlieb is Caucasian, and her 1-year-old son, Jordan, is mixed race. As the head coach of the University of California’s women’s basketball team, Gottlieb travels a lot, and has never had anyone question whether her son was hers, until this week when she was flying with Southwest.

“Ticket counter personnel told me I had to ‘prove’ that he was my son, despite having his passport,” she tweeted at the airline. “She said because we have a different last name. My guess is because he has a different skin color.”

The incident happened when Gottlieb was travelling from Denver to Oakland. She says the airline employee first asked her for a birth certificate even though she was carrying Jordan’s passport, and then asked her to prove her son’s parentage with a Facebook post.

(Note: Most airlines, including Southwest, do require a birth certificate is required to validate the age of all infants under age two, so it’s best to carry it with you even if you do have baby’s passport).

Gottlieb says the mother next to her in line said that’s never happened to her, despite the fact that she, too, had a different last name than her child. When Gottlieb tweeted about the incident though, other parents who’ve been through similar situations, including Chrissy Teigen, chimed in. According to Teigen, airlines may ask to prevent child trafficking.

This isn’t the first time a mom has taken to social media after Southwest asked for a birth certificate. Last year, another mom posted to Facebook after she was forced to buy and seat for her infant daughter because without a birth certificate, she couldn’t technically prove the baby was under two.

In the more recent case, it wasn’t the request for the birth certificate that was the real problem: It was the way the employee spoke to Gottlieb. While we don’t know exactly what was said, it’s clear Gottlieb felt like her motherhood was questioned because of her child’s race, which isn’t acceptable.

Southwest says it is coaching the employee, and the company apologized to Gottlieb. “We apologize if our interaction made this family uncomfortable — that is never our intention,” the airline said in a statement.

“Southwest Airlines’ policy is to verify lap children are younger than the age of two by reviewing a birth certificate or government issued identification. Certain international locations require us to verify additional paperwork for those travelling with a minor. Domestic travel does not require carriers to match last names of a child and guardian.”

Gottlieb told the Associated Press she appreciated the apology, and that she recognizes her privilege. “While it was upsetting and emotional, I realize that this was just one day of my life where I was uncomfortable and our family was made to feel ‘less than’ whereas others face similar situations on a daily basis,” she said.

She hopes her tweet storm ensures “that all families — regardless of how ‘traditional’ they may or may not look — are treated with dignity and respect.”

You might also like: