When you define adult, the answer will vary greatly. For instance, you are considered an adult generally at the age of 18 but there are some places where that age is 19. Additionally, if you really wanted to know, you can check the profile of the person and use their birthdate to determine their age.
It is not recomended to ask people under 18 for their age.
My answer is: it depends on what age you consider adult
TPBM has lied about something and regreted it.