// Register single-optin widget area
genesis_register_widget_area(
	array(
		'id'          => 'single-optin',
		'name'        => __( 'Single Optin', 'my-theme-text-domain' ),
		'description' => __( 'For email option subscription widget', 'my-theme-text-domain' ),
	)
);

// Display single-optin widget area on single blog posts other than those categorized under "category-2"
add_action( 'genesis_after_header', 'sk_single_optin' );
function sk_single_optin() {

	// if we are not a single post page, abort.
	if ( !is_singular( 'post' ) ) {
		return;
	}

	// if the current post is not in "category-2" (slug), abort.
	if ( !in_category( 'category-2' ) ) {
		return;
	}

	genesis_widget_area( 'single-optin', array(
		'before'	=> '<div class="single-optin widget-area"><div class="wrap">',
		'after'		=> '</div></div>',
	) );

}