Gioachino Antonio Rossini the popular Italian composer composed operas, sacred music and chamber music. His affect on music today would be highly subjective and would need research on the modern composers - biographies etc - to see if in fact his music influenced any modern composer. Some basic links are listed below that should help your research.
If Rossini's music had to be summed up into one word, I think the best word would be 'loud.' Rossini is affectionately known in music circles as 'Senor Crescendo.' 'Quaint and truculent' are biographers' descriptions of both Rossini himself and his music. His music is further described as having 'humor, grace and vivacity.' Rossini composed 13 operas in his 30 year career. Among his most famous ones are The Barber of Seville, Othello, and William Tell. Part of the William Tell Overture gained fame in the 1950s as the theme to 'The Lone Ranger' TV series. This theme ranked second only to the theme from 'Dragnet.'
Gioachino Antonio Rossini 29th February 1792 to 13th November 1868 died at his country house at Passy and was buried in Père Lachaise Cemetery, Paris, France.
No, he was an only child.