Why do hereditarians love the word "empirical" so much?

In this post I cite examples of hereditarian IQ/race/genetics researchers (Robert Plomin, Ian Deary, etc.) using appeals to "empirical" evidence to support their views. Their use of the word "empirical" specifically to defend themselves against their critics recurs weirdly often to the point where they seem to "get off" on using this word. And often their uses of it seem entirely redundant in the context in question. All emphases that follow are mine.

Example 1: "Concerning the equal environments assumption in general, empirical data based on most twin studies ever published point to little or no influence of shared environmental factors on twin similarity" (Arden et al. 2016). 

Example 2: "A theoretical logic provides a useful framework for considering the empirically discovered links between intelligence and health. This framework is useful in generating empirical research questions such as ours" (Arden et al. 2016).

Example 3: [After describing E.G. Boring's 1923 quote "Intelligence is what the tests test"] "The apparently dismissive comment came after a summary of strong empirical findings — for example, that the tests showed marked individual differences, that the differences were stable over time, that children developed greater intelligence over time but tended to maintain the same rank order" (Deary et al. 2010, p. 202).

Example 4: "[Psychologist Howard] Gardner has intentionally avoided empirical tests of his theory [of multiple intelligences or MI], but those that have been made show most of his MI to be correlated with one another...The theories that do not accommodate this finding [referring to the positive correlations between different mental tests] — such as those of Thurstone, Guilford, Sternberg and Gardner — fail the most basic empirical tests" (Deary et al. 2010, p. 204).

Example 5: "More than 100 years of empirical research provide conclusive evidence that a general factor of intelligence (also known as g, general cognitive ability, mental ability and IQ (intelligence quotient)) exists, despite some claims to the contrary" (Deary et al. 2010, "Key points").

Example 6: "...we estimated the heritability of height from empirical genome-wide identity-by-descent sharing..." (Visscher et al. 2006)

Example 7: "...the empirical variance of IBD sharing is likely to be an underestimate because the marker information was not perfect" (Visscher et al. 2006).

Example 8: "They also failed to highlight that the theoretical discussion actually revolved around
an empirically testable question...To conduct the test, I drew on an empirical model..." (Littvay 2012)

Example 9: "The findings place the burden on critics to present theoretical work on the specific mechanisms of EEA violations based on which additional empirical assessments could (and should) be conducted." (Littvay 2012)

Example 10: "...these criticisms, like most of the literature questioning the validity of the EEA [equal environments assumption], are made on the basis of secondary analysis of published research, not on the basis of empirical examination of CTD [classical twin design] assumptions on political variables." (Smith et al. 2012, p. 19)