SERPENT-SEED DOCTRINE, is it true...?

Here's a link to great search engine, the Blue Letter Bible

Type in the word "SEED " & click "Search".

Spend ten minutes or so reading the contextually related responses....  Then draw your own conclusion. 

Regardless of what you determine, never forget this verse...

Gen 3:15And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel.

...and it's fulfillment at the cross !

Eph 2:15 Having abolished in his flesh the enmity, [even] the law of commandments [contained] in ordinances; for to make in himself of twain one new man, [so] making peace;
16 And that he might reconcile both unto God in one body by the cross, having slain the enmity thereby:

Jesus died so that everyone might live.