Add line breaks in WordPress site description of Genesis child theme by using commas, then using PHP preg_replace to replace commas with line breaks in site description.

functions.php

<?php
// don't copy php tag

// genesis replace default description with description containing line breaks
remove_action( 'genesis_site_description', 'genesis_seo_site_description' );
add_action( 'genesis_site_description', 'child_seo_site_description');
function child_seo_site_description() {
	$blogdesc = get_bloginfo('description');
	$blogdesc = preg_replace("/, */", "<br>", $blogdesc); ?>
	<p id="description"><?php echo $blogdesc; ?></p>
<?php }