I see, pure speculation, i suppose you also don't take it into account that many of these supposed Germano-Poles were forcibly conscripted?
Not pure speculation at all. Data released by the British government in conjunction with the Polish government-in-exile. But do feel free to give the traditional Polish reaction when faced with uncomfortable facts from the past, i.e. deny, deny, deny.
As for evidence, have a look at Hansard from 1946 or Dr Mark Ostrowski's excellent book "To Return To Poland Or Not To Return: The Dilemma Facing The Polish Armed Forces At The End Of The Second World War". Here's chapter one: angelfire.com/ok2/polisharmy/chapter1.html
And of course it's absolutely impossible than any one of them were ethnic Germans living in Poland before the war.
89,300 is the number of Poles who joined the Polish army after having first been captured while members of the German armed forces. 15,517 is the number of Poles who were captured by the British while fighting in the German armed forces but did not join the Polish army. 89,300 + 15,517 = >100,000 And that's before we've started to count the Poles who were not captured. Do you have any proof that they were not Poles?