Do isoflavones affect penis growth in a negative way ?

Depends upon timing?: Also, are we talking rodent penis or human? Seriously! As our knowledge base increases, often our opinions change. For a long time, soy based protein was de rigueur. Now we worry about its effects on human males, especially b/c its isoflavones, while helpful in one way, can potentially be harmful in another. Check out http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257624/ for possible timing issues.