After the battle of Kurukshetra, when Yudhisthir had performed the funeral rites of Karna,his mother Kunti told him that Karna was his real brother. He was so infuriated by his mother for withholding this secret from him that he rebuked her and cursed all womankind that they would never be able to hold a secret ever again.
A survey commissioned by the telegraph said that women cannot keep a secret for more than 47 hours. This survey was conducted amongst 3000 women between the age of 18-47.
You will notice that among babies,girls start talking much earlier than boys. Also girls talk much more than boys. It is in the inherent nature of girls to talk more and have more to do with words. Thus when it comes to secrets they feel an urge to communicate it.
Researchers from Tuft University have gathered that holding a secret for a woman seems like a mental burden. Thus they like to discuss their secret.
Women have a curious nature. They have a need to know things and tell things. Thus it is very difficult for women to keep a secret.
Telling a secret can also be a means to get attention amongst peers. It is a way to gain another person's trust. Though this is wrong but sometimes this is the intention.