To summarize what many have already said.
My suggestion for is that there is one likely culprit for most headless homebrew — bad fermentations.
I think that most headless homebrews result from beers with too many “head killers” in them. Specifically, I’m thinking of some of the foam killing molecules — such as higher alcohols (or “fusel oils”) — that result from fermentation temperatures that are too high or worts that are underpitched. In most cases, I believe there are enough foam positive elements in the beer, but these are negated by fermentation byproducts that kill foam. (Note that Belgian yeasts and German wheat yeasts both reputedly produce lower levels of fusel oils than normal brewers yeast strains, especially at higher fermentation temperatures.)
In addition, when yeast are stressed during fermentation, they secrete proteases in larger amounts than unstressed yeast do. Stress may result from underpitching, underaeration or high-gravity fermentation
. The resulting protease activity may decrease the amount of beer foam in the resulting beer.
Other things to consider:
hopping rate (use hops with high alpha acids)
adding wheat malt, carapils or crystal malt
inadequate protein rest
low mash temp
not using a one hour boil
lowering alcohol by lowering OG
Here a good article from BYOhttp://www.byo.com/stories/article/indices/35-head-retention/697-getting-good-beer-foam-techniques