Although it is a common response, it’s insensitive and plays into stereotypes.
Things Not To Say To Your LGBT Coworkers
#1 “I suspected you were gay.”
#2 “I’m sorry.”
Why should you apologize for a colleague’s orientation? This implies judgment and can make the situation more difficult. Would you apologize for a person’s ethnicity or gender?
#3 “Why did you tell me that?”
It’s important for people to bring their “whole selves” to work, and coming out of the closet is certainly a part of who one is. It is rude to question a coworker’s intention to share his or her whole self with you.
#4 “We are not close enough for you to share that information with me.”
Not all employees are interested in their coworkers’ personal lives. If you feel a colleague may have shared too much information, you can simply say, “Thank you for telling me that.”
#5 “So, Who is the man?” or “Who is the woman?”
If you have a singular, hetero-normative view about relationships, you might wonder how same-sex relationships work. But questions like this are insensitive and inappropriate.
#7 “Which bathroom do you use?”
#8 “So, you are woman or man now?”
Transgender people often are asked what gender they are. Such questions are inappropriate. It is important to remember that gender identity is becoming an increasingly sensitive subject.
Source: DiverysityInc’s article 7 Things NEVER to Say to LGBT Coworkers by Daryl Hannah