Ethel,
I don't know if your opinion is just based on this site or on a deeper investigation.
I used to believe this but then went off to investigate it after one of Loosehead's little "cut them off" rants intent on proving him wrong but what I found changed my mind.
Take this paper:
http://www.jaapl.org/cgi/content/full/33/1/16 (Journal of the American Acadamy of Psychiatry and Law)
The studies of bilateral orchiectomy are compelling in the very low rates of sexual recidivism demonstrated among released sex offenders.
From memory I think the highest case of recidivism was about 15% -(chemical) - but I don't have the references to hand right now.
You can twist that and say that there are "numerous cases of molestation" but we're talking about a better than 85% result.
That is very very far from useless in my humble opinion!
Oldgrape I'd keep my eyes open and my mouth firmly shut if I were you - anonymous letters and the like have a habit of finding their way home when investigations are started and your sister in law could get in more trouble than just losing her job