Table schema:
CREATE TABLE table_name_79 (genre VARCHAR, release_year_of_first_charted_record VARCHAR, country_of_origin VARCHAR)

Question: What is the Genre, when the Release-year of first charted record is 1968, and when the Country of origin is United States?
SQL: SELECT genre FROM table_name_79 WHERE release_year_of_first_charted_record = 1968 AND country_of_origin = "united states"