What are the motifs in The Tin Drum by Gunter Grass?

Sexuality is a key component of The Tin Drum. Yet, it is often a perverse type of sexuality involving manipulation, incest, adultery, or pedophilia. It is unclear if this is a commentary on the era, a remnant of Victorian ethics, or simply a reflection of Grass's worldview. The novel contains many alliances and liaisons, but is devoid of a single example of mutual attraction between unattached equals. Initially, Joseph Wranka hides under a Kashubian stranger's skirts, impregnating her in the process. Oskar also hides under these accommodating skirts as an infant, and longs for the security of the enfolding fabric throughout his life. This longing takes on incestuous overtones when a young adult Oskar peers up his grandmother's "opening" and describes the visions of ancient Poles he sees inside her womb.