Finding out that the child you love is not biologically your own must be one of the most heart-breaking revelations any father could endure.

And now stricken dads have opened up about the moment they realised their children did not really belong to them.

Taking to the secret-sharing app Whisper, the anonymous fathers have revealed how they finally uncovered the truth about their children's biological parentage.

The incredible admissions range from a man who was not told the truth about his child for 19 years, to another who only uncovered the secret about his child after snooping through his partner's journal.

Finding out that a child you have cared for and loved for decades must be one of the most heart-breaking revelations any parent can endure

Devastated fathers have been opening up about their experiences on the secret sharing app

Some were just supicious, while others found definite proof that they were not the father

One dad only uncovered the secret after snooping through his partner's journal (file photo)

Some of the fathers revealed that although they were shocked by the revelation, they nevertheless loved their children and would continue to support them

The shocking tales came to light through the anonymous secret sharing app, Whisper

Some fathers found out the news early on, for others it was after years of raising their child

There were traces of bitterness towards some of the mothers in the quotes shared on the app

It seems some fathers would perhaps prefer the truth about their child to be kept from them

Fathers took the opportunity to tell their tales and share their pain via the app