I don't buy this. I am the oldest, measuring in at 6 feet. My younger brother is at least 6 ft. 3 in., and my sister the youngest measures at almost 6 ft. 2 in. Obviously neither my brother or sister suffered in terms of height from being younger siblings...unless you count the fact that none of us became quite as tall as my dad, who measured 6 ft. 6 in.

Emily, Kawasaki, Japan

Rubbish! My parents had 5 children, 4 girls then a boy, each one taller than the last except for the third child, who is the tallest girl by 3 inches. The youngest, the only boy, is tallest by an inch and is about an inch taller than our father.

I would suggest that the age difference between siblings is a huge factor in this. My family is spread over 14 years: 1st child -> 18 months -> second child -> 3 years -> 3rd child -> 5 years -> 4th child -> 5 years -> 5th child.

I would say that this theory rings true only for the first 2 children because although number 2 is taller than number 1 by 2 inches, she is of a much lighter build - a natural size 6/8 compared to a natural 10.

However, this particular type of build runs through the family on my fathers side though our grandmother, as number 2 looks very similar to her half-auntie, my dads half-sister, and various of my nieces and nephews have inherited it also.

So put that into your genetic model! No really, do!

Liz Scott, Gutersloh, Germany

All I can say is that it was not always so!!! I am the eldest of four and I was born in 1935. I reached the great height of 5ft 3ins. My brother who is two years younger is 6ft 1in. My sister was 5ft 8ins -- shorter now thanks to two back operations-- and the baby of the family, another brother is 6ft 2ins. My mother always blamed errant genes as my maternal grandmother was 5ft and my maternal grandfather was 6ft 4ins. Our family has been a right old mixture ever since. My mother who was the second born was the tallest of her female siblings at 5ft 6ins with an elder sister at 5ft 3ins and a younger one at 5ft 1in and a baby brother who just about topped 5ft 8ins.We are a fairly prolific family and your findings just do not fit us at all. The exception that proves the rule perhaps!

Sheila Cross, Huntingdon, England