Table 5

0 Probable biological parent.

1 Age difference between parent and child improbable (outside the range 15-49 for mothers and 15-64 for fathers).

2 The link was only established because the parent was married to another parent.^a

3 Detailed relationship codes explicitly specify a step-parent relationship—information not available in 1850-1870, 1960, 1970, or 1980.

4 Mother has zero children ever born (1940-1990) or zero children surviving (1900-1910)—information not available for 1850- 1880, or 1920.

5 Detailed relationship codes specify that the child is adopted—information available only for 1850-1880, 1900, 1910, and 1920.

6 Child was born before marriage of parent and there is a mismatch between parental birthplace on child's record and birthplace of parent. Available only for 1900 and 1910.

7 For STEPMOM: Number of children present exceeds number ever born (or, for 1900 and 1910, number surviving), and child was born before marriage of mother (current marriage in 1900, 1910, and 1950; first marriage in other years)—information not available for 1850-1880, 1920, 1990, or the 1970 Form 2 samples.

7 For STEPPOP: Surname differs and child is a male or never-married female (female under age 15, 1850-1870). Available only for 1850-1880, 1910, 1920, 1940, and 1950.

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