How does this work?

[Espalier]

Last year I was 38. My father was born in 1938. This made him 67. I was born in 1967. Coinsidence?

I've tried this out with a few other people, and there seems to be a pattern.

Start date is parents year of birth - eg 58

The year the sibling will be 58 years old - eg 2049

The difference betwen siblings age now and age in 2049 plus age of parent now equals siblings year of birth.

Any ideas.

[bongerman]

Let a = last 2 digits of parent's DOB

Let b = last 2 digits of child's DOB.

Assume both born in 1900's.

The year child will be a years old = 1900+a+b

The difference between child's age now and age in (1900+a+b) is:

1900+a+b - 2006

add on the age of parent now gives:

1900+a+b - 2006 + (2006 - (1900+a)

simplifies to

1900+a+b-2006+2006-1900-a

= b

ie the child's year of birth.

[beerbelly]

Spooky !!!!

[mahonia]

Think I'll stick to crosswords!

[mkt]

wow this is really cool! New party trick. Thanks!