3. Differences in Background.--Even though both man and wife come from good homes, if those homes are widely different in standards and in cultural background strains may develop in later life between the couple. Differences in race, religion and age are recognized as having a causative relation to desertion. Miss Brandt[9] found that, in about 28 per cent of the cases where these facts were ascertained, the husband and wife were of different nationality. "In the general population of the United States in 1900 only 8.5 per cent was of mixed parentage, and for New York City the proportion was less than 13 per cent.... A difference in nationality was more than twice as frequent among the cases of desertion as among the general population of the city where it is most common." Miss Brandt's figures for difference of religion are less significant, but it existed in 19 per cent of the total number of cases for which information on this point was available. In 27 per cent of the families where age-facts were learned, there were differences of over six years between the two; in 15 per cent the woman was older than the man. Other differences which should find mention under this heading are those that arise when the environment is changed by immigration. The man who precedes his wife by many years in coming to America has often outgrown her when she finally joins him, even if he has formed no other family ties. The handicap is not wholly overcome when the couple come to this country together, for the much greater opportunities of the man to learn American ways may drive a wedge between him and his wife. On the other hand it is a popular saying, particularly among young Italian immigrants, that girls who have been in America too long do not make good wives, that when a man wants to marry he had better send for a girl from the old country; and these marriages seem on the whole to turn out well. 4. Wrong Basis of Marriage.--Included here should be hasty marriages, mercenary marriages, marriages entered into unwillingly after pregnancy had occurred, as well as marriages where coercion was a factor for other reasons.[10] When there have been sex relations before marriage, unless the custom of the community sanctions such intimacy, there are likely to develop jealousies, quarrels, and ill feeling. "He do be always castin' it up at me, but sure, 'twas himself was to blame" is one version of the age-old story. There should also be included here those irregular unions called "common law marriages," which are still permitted in many of our states. The protection supposed to be afforded to the woman by this institution is mainly fictitious, as it is practically impossible to secure conviction for bigamy if one of the marriages was of the common law variety. A common law husband who deserts, even if he admits his wife's legal claim upon him, does not feel morally bound; and this fact undoubtedly plays its part in the causation of such desertions.[11]