David Wells, Bryant's adviser, told ESPNDallas.com Tuesday that the former Oklahoma State wide receiver was asked about his mother during a visit to the Dolphins in March, prior to the NFL draft.
Yahoo! Sports, which was first to report the story, also revealed that it was Ireland who asked the question of Bryant.
Wells and Bryant declined further comment.
"My job is to find out as much information as possible about a player that I'm considering drafting. Sometimes that leads to asking in-depth questions," Ireland said Tuesday in a statement released by the Dolphins. "Having said that, I talked to Dez Bryant and told him I used poor judgment in one of the questions I asked him. I certainly meant no disrespect and apologized to him."
Ireland received permission from the Cowboys' front office Tuesday to speak with Bryant.
Yahoo! Sports reported that during one of his pre-draft visits, Bryant was asked by a high-level executive of one NFL franchise -- during an extensive conversation about Bryant's past -- whether his mother, Angela, was a prostitute.
"No, my mom is not a prostitute," Bryant told Yahoo! Sports. "I got mad -- really mad -- but I didn't show it. I got a lot of questions like that: Does she still do drugs? I sat and answered all of them."
The background of Bryant and his mother was widely reported prior to the draft. Angela was only 15 when Dez was born, and she served time in jail for selling crack cocaine.
NFL Players Association executive director DeMaurice Smith lashed out at the line of questioning Ireland used.
"We need to make sure the men of this league are treated as businessmen," Smith said in a statement. "During interviews, our players and prospective players should never be subjected to discrimination or degradation stemming from the biases or misconceptions held by team personnel.
"NFL teams cannot have the free reign to ask questions during the interview process which can be categorized as stereotyping or which may bring a personal insult to any player as a man. For the past year, active, former and incoming players have heard me speak about the expectations we have of them as members of this union, their teams, communities and families. It is equally true that the same kind of respect is demanded of their employers."