Hello Good Evening,
Virginity mainly based on inactivity of Hymen
Hymen is intact in a virgin female where in a deflorated woman it is usually not intact.
A doctor can only determine whether a woman has a hymen or not; this does not give an indication of virginity or sexual experience.
Some females who have never had sex do have an intact hymen. Not all females however are born with hymens; it's also quite common for the hymen to naturally rupture due to athletic activities, injury
, use of tampons or penetrative masturbation
. Not all females bleed or experience pain, upon first time vaginal sex.
Also, some women who have had sex still have part of a hymen; a hymen may not fully rupture during early sexual experiences or even until childbirth. This is because some hymen tissue can stretch during penetration, instead of rupturing.
So you can convince your parents by above description, but only with the help of doctor.
Dr. Naresh Jain