code: private LocalDate ancestorAdjustment(final LocalDate date) {
          if (date == null) {
              return null;
          }
          return date.plusYears(typicals.ageAtMarriage()
                  + typicals.gapBetweenChildren())
                  .withMonthOfYear(1).withDayOfMonth(1);
      }
docs: Apply a standard adjustment from an ancestor's marriage date to a
  person's birth date.
  
  @param date the ancestor's marriage date
  @return the adjusted date