filter-genesis-post-info.php

<?php
add_filter( 'genesis_post_info', 'lc_post_info' );
/**
 * Filter the Gensis post info to not include the "by" component if
 * the post type does not support authors.
 */
function lc_post_info() {

	$post_type = get_post_type();

	if ( ! post_type_supports( $post_type, 'author' ) ) {
		return '[post_date] [post_author_posts_link] [post_comments] [post_edit]';
	} else {
		return '[post_date] ' . __( 'by', 'genesis' ) . ' [post_author_posts_link] [post_comments] [post_edit]';
	}
}