Why are parents such liars?

When will people learn not to lie? I've been to to all my life and mainly by my parents but this time I'm talking about my father keeping a huge secret from me till I was old enough to know.

My father had always told me he and been married twice and I believed him. I came across one of his photo albums and asked who the woman in the picture was and he said it was his first wife but I knew he was lying as the person in the photo looked nothing like her.

My parents were going through a rough time and were heading for a divorce. One night when I was about 16, my father told me that he had been married three times and I had an older half sister who he hasn't been in contact with since she was four years old. He told me she would then be in her late forties and maybe wanted nothing to do with him.

The next morning something happened. My father was actually crying and holding a long letter in his hand and panicking. The letter was actually from the long lost daughter who was trying to find him. They spoke on the phone and exchanged letters a few times and I even met up with her and her kids and husband twice.

Just before my parents divorced I went into my dads bedroom and found a card that was ripped in half and put into the trash. I was shocked had they had a row? They were such a lovely family. I asked my father what had happened and he said he wanted to keep away from her and never mention her name again.

I still want to know what's happened to him. She found him after all these years and he's just rejected her for no reason. He also told me I have an older brother who was put up for adoption at birth in London if anyone knows anything about this please contact me.