What's your position bout the birth of twins? some say its hereditary factor while some say its an abnomality in fetilization due to accidental discharge.

I will say it is both. Families with history of twin births produce it more regularly and going by science it is also fertilization of more than one egg at a time and or separation of already fertilized egg to give unidentical and identical twins respectively.
This topic should be in family section. Mod and op, take note.