You would have to eat a large number of Peach seeds to poison yourself or someone else. Not only peaches, but
almond seeds and apricots as well as apple seeds and cherries all produce cyanide.
Which is called prussic acid by another name, or hydrogen
cyanide.
Prussic acid was one of the poisons that victorian murderers used.

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"You will never find a real Human being - Even in a mirror." ....Mike Kremer.