See e.g. Havelock Ellis, The Criminal, 4th ed., 1910, chap IV.

R.L. Dugdale, The Jukes, 4th ed., 1910. It is noteworthy that Dugdale, who wrote nearly forty years ago, was concerned to prove the influence of bad environment rather than of bad heredity. At that time the significance of heredity was scarcely yet conceived. It remains true, however, that bad heredity and bad environment constantly work together for evil.