So, I found US death data by age and sex for 2007 ( http://www.cdc.gov/nchs/data/dvs/mortfinal2007_worktable310.... )

Here are male deaths, expressed as a percentage of female deaths, for every year of age from 0 to 30:

     0  127%
     1  119%
     2  130%
     3  131%
     4  142%
     5  138%
     6  123%
     7  129%
     8  122%
     9  125%
    10  126%
    11  152%
    12  143%
    13  145%
    14  178%
    15  193%
    16  199%
    17  248%
    18  278%
    19  313%
    20  317%
    21  317%
    22  342%
    23  310%
    24  314%
    25  291%
    26  261%
    27  269%
    28  250%
    29  231%
    30  237%

Odds are good (I haven't checked) that the male population in this age range is larger than the female population. But it's going to be larger by less than 10%, which is completely neglible in the face of the factor-of-2-or-3 differences in deaths.

This isn't "little role in early-life mortality", it's a gargantuan genetic effect you'd have to devote quite a lot of effort to ignoring. (And if you meant something different by "early life", male deaths stay in the range of 150-200% of female deaths right up until the early 60s. Female deaths finally exceed male deaths once people hit 80 years old.)