Nobles were born into a noble family, adopted by a noble family (this was abolished in 1633) or ennobled by a king or Sejm for various reasons (bravery in combat, service to the state, etc.yet this was the rarest means of gaining noble status). Many nobles were, in actuality, really usurpers, being commoners, who moved into another part of the country and falsely pretended to noble status. Hundreds of such false nobles were denounced by Hieronim Nekanda Trepka in his Liber generationis plebeanorium (or Liber chamorum) in the first half of the 16th century. The law forbade non-nobles from owning nobility-estates and promised the estate to the denouncer. Trepka was an impoverished nobleman who lived a townsman life and collected hundreds of such stories hoping to take over any of such estates. It does not seem he ever succeeded in proving one at the court. Many sejms issued decrees over the centuries in an attempt to resolve this issue, but with little success. It is unknown what percentage of the Polish nobility came from the 'lower' orders of society, but most historians agree that nobles of such base origins formed a 'significant' element of the szlachta.
When did the denouncing of many nobles take place?
first half of the 16th century

In the oft-cited and oft-criticized Sexual Behavior in the Human Male (1948) and Sexual Behavior in the Human Female (1953), by Alfred C. Kinsey et al., people were asked to rate themselves on a scale from completely heterosexual to completely homosexual. Kinsey reported that when the individuals' behavior as well as their identity are analyzed, most people appeared to be at least somewhat bisexual i.e., most people have some attraction to either sex, although usually one sex is preferred. According to Kinsey, only a minority (510%) can be considered fully heterosexual or homosexual.[citation needed] Conversely, only an even smaller minority can be considered fully bisexual (with an equal attraction to both sexes). Kinsey's methods have been criticized as flawed, particularly with regard to the randomness of his sample population, which included prison inmates, male prostitutes and those who willingly participated in discussion of previously taboo sexual topics. Nevertheless, Paul Gebhard, subsequent director of the Kinsey Institute for Sex Research, reexamined the data in the Kinsey Reports and concluded that removing the prison inmates and prostitutes barely affected the results.
Why do people say KInseys work is not correct?
the randomness of his sample population,

In Charleston, the African American population increased as freedmen moved from rural areas to the major city: from 17,000 in 1860 to over 27,000 in 1880. Historian Eric Foner noted that blacks were glad to be relieved of the many regulations of slavery and to operate outside of white surveillance. Among other changes, most blacks quickly left the Southern Baptist Church, setting up their own black Baptist congregations or joining new African Methodist Episcopal Church and AME Zion churches, both independent black denominations first established in the North. Freedmen "acquired dogs, guns, and liquor (all barred to them under slavery), and refused to yield the sidewalks to whites".
How many African Americans lived in Charleston in 1860?
17,000