hover over a div and adjacent div changes color

<b>sibling method:</b>
<div>
    <div class="sibling-hover">hover over me</div>
    <div>I do nothing</div>
    <div>I do nothing</div>
    <div class="sibling-highlight">I get highlighted</div>
</div>

<b>child method:</b>
<div id="parent">
    <div>hover over me</div>
    <div>hover over me</div>
    <div>hover over me</div>
    <div class="parent-highlight">I get highlighted</div>
</div>