Determining a patients biological age?
As the definition of biological age is very ambiguous, I propose that to generate an algorithm, you first need to create a quantifiable definition. I submit:


  Biological age is a measure indicating what portion of one's calculated life expectancy is already expended, adjusted proportionately for the average life expectancy of their major demographic.


Wow, that's a mouthful! So, let's break it down.

Life expectancy is calculated :


Ascertain a person's major demographic (Geographic residence, Race, Gender and Generation).
Find the average life span of that demographic.

This is negligibly speculative as a living person's Generation has not yet fully perished
Statistical outliers, such as infant mortality, are generally excluded from this calculation

Adjust for known major factors that have accepted statistical impact.eg:

Lifestyle
Current medical conditions
medical history



Average Life expectancy of subject's demographic was calculated in #2 above.

So, now let's throw in some sample numbers.

Statistical Facts: (totally made up)


Caucasian males living in the France, born in the 1970s have an average life span of 72 years.
Exercising 30 minutes or more daily increases life expectancy 6 years
Smoking decreases life expectancy 7 years
Not smoking increases life expectancy 2 yearsHold on a second?! Wouldn't not smoking already be accounted for in the "Smoking..." section? Well, no, because our demographic sample are all "unknown" so having specific knowledge would statistically change the results in either direction
Heart Disease decreases life expectancy 8 years
Devout religious affiliation increases life expectancy 6 years.
Family history of diabetes decreases life expectancy 2 years.


Two subjects both Caucasian, french males born in 1974 (40 years old chronologically):Their mom's actually shared a labor and delivery room!


Beavis - known: Smoker with heart disease.
Butthead - known: Devout Buddhist, very athletic, non smoker with a family history of diabetes

Beavis' life expectancy is 57 (72-7-8)Butthead's life expectancy is 84 (72+6+2+6-2)

Beavis has expended 70.2% (40/57) of his life expectancyButthead has expended 47.6% (40/84) of his life expectancy

Despite sharing a birthday:Bevis' biological age is 50.5 years (.702*72)Butthead's biological age is 34.3 years (.476*72)


Note: It's almost 6 hours past my bedtime, so please excuse any stupid mistakes or miscalculations.  The general concepts are what is important