Many a parent has sat their little one down, and in hushed tones told them that they will be getting a new baby brother or sister soon but that “Mummy and Daddy will still love you just the same”. Children, I’m here to tell you this is a lie.

Not only is it a lie, but it will be demonstrated here, complete with mathematical proof.

Let’s consider a situation where there is one parent and one child. Let L represent the amount of the parent’s love for that child. L is 100% for the first child. When the next child arrives, and assuming the parent loves both children in equal quantities (ignoring favourites) the value of L reduces to 50%. So far, it’s simple.

Let N represent the number of children. The simple formula for the Parental Love Quotient, Q is:

PLQ = L / N

As N increases, PLQ tends towards zero, never actually reaching it.

Several assumptions are made:

1. The total of parental love available to all children remains unchanged over time.
2. The parent does not favour any one child.
3. Multiple simultaneous births are excluded for the purpose of simplicity.
4. Both parents love their children in equal amounts.
5. The love for any one child remains a constant value until the next is born.
6. Ginger stepchildren are excluded from the mathematical model.

It’s clear that these assumptions are prone to challenge, but for the initial explanation, let’s keep the number of variables low.

This graph charts the PLQ from 1 to 16 (Catholic) children:

It also shows another interesting value; the Size Of Lie (SOL). This is the size of the lie told to each succeeding child. Note that the SOL value diminishes greatly as the number of children increases. The first child is lied to the most.

The formula for Size Of Lie is:

SOL = PLQ_n – PLQ_n-1

With regard to the assumptions laid out above, a Favourite Child Weighting value must be factored in when calculating the PLQ values for your own family. This will also help determine the Size Of Lie from one child to the next and indicates how evil your parents are.

The above theorem will be included in my forthcoming book “Grow Up, Imbecile” which challenges many accepted precepts of family life, but adds a scientific or mathematical viewpoint in order to illuminate hitherto unquestioned dogma.